How to set up an ad hoc network through a VPN

[Deleted]

Hello every one,
I need help establishing an ad hoc network that goes through my VPN and not my ethernet cable.
Here are the details: I live in a college residence and the internet connexion is blocked on pretty much everything. I found that only a VPN using SSTP works to play games and such. I bought a 3DS last week to play at the new pokemon game, but I can't connect to the internet with it, so I tried to establish an ad hoc network but when I join the ethernet cable with my usb wifi adaptor(I don't have a wifi card on my desktop) to create the ad hoc network, I couldn't connect to the internet with my 3DS. So I need to join my VPN connexion and the usb wifi adaptor to create the ad hoc network so I can create a wifi hotspot which I can use to connect to the internet with my 3DS, but i don't know how.

I tried using connectify hotspot, it seems like it is doable but only on the paid version and for some reason, they are refusing my credit card(which works fine btw). So my last resort is to get some help^^

I forgot to mention I am on windows 8.1.